Latch mechanism



Nov.- 12, 1963 w. R. scALF ETAL LATCH MECHANISM 2 Sheets-Sheet l FiledNov. 6, 1961 INVENTORS.

Nov. 12, 1963 w, R. scALF ETAI.

LATCH MECHANISM 2 Sheets-Sheet 2 Filed Nov. 6, 1961 AT. RNEYn I UnitedStates Patent 3,1lt,512 LATCH MECHANISM William R. Scalf, Milwaukee, andGlenn G. Stoddard, South Milwaukee, Wis., assignors to General MotorsCorporation, Detroit, Mich., a corporation of Delaware Filed Nov. 6,1961, Ser. No. 150,519 3 Claims. (Cl. 292-5) This invention relates to-latch mechanisms and in pa ticular to an improvement thereof formaintaining the mechanism locked in opened or closed positions.

One form of latch mechanism in the prior art comprises two rods disposedin parallel with respect to each other and mounted within a door. Eachof the rods is provided having a rack portion formed thereon. A pinionis interposed in meshing engagement with the rack portions. An actuatinghandle is iixed with the pinion and serves to rotate the latter so as toobtain axial movement of the rods into or out of engagemnt with suitablekeepers. In addition, the handle is provided with a latch member whichrotates into or out of engagement with a third keeper simultaneouslywith the rods. However, latch mechanisms as described do not provideadequate means for maintaining the mechanism locked in opened or closedpositions so that for example once the door is closed and latched thelatch mechanism will remain locked until it is desired Ito open thedoor.

In -accordance with this invention, a latch mechanism of the typeincluding a pair of rods or latch bolts having rack portions formedthereon and driven by a handle actuated pinion interposed in meshingengagement with the rack portions may be maintained locked in opened orclosed positions. This is accomplished by using a latch member which isrotatablewith the pinion and a lock block which is spring biased forengagement with the latch member. The latch member may be formed havinga cam surface interposed lbetween bearing surfaces on the latch membercorresponding to latch opened and closed positions. The cam surface camsagainst the spring biased lock block as the latch member is rotatedbetween latch opened and closed positions. To reduce Wear on the lockblock, the cam surface may he a sur-face of a captivated slide elementmounted on the la-tch member. This arrangement is especially adapted forthree-point latch mechanisms wherein the latch member may serve as arotary latch arm with an associated keeper.

A more complete understanding of this invention may be had from thedetailed description which `follows taken with the accompanyingydrawings in which:

FIGURE 1 is a front elevational view of one embodiment of the invention;

FIGURE 2 is a side Iview taken on line 2 2 of FIG- URE l looking in thedirection of the arrows, with parts broken away and in section;

lFIGURE 3 is a rear View substantially on line 3-3 of FIGURE 2 lookingin the direction of the arrows, with parts broken away and in section;

FIGURE 4 is a sectional View taken on line 4--4 of FIGURE 2 looking inthe direction of the arrows;

FIGURE 5 is a sectional view taken on line 5-5 of FIGURE 2 looking inthe direction of the arrows;

FIGURE 6 is an exploded perspective View showing the latch arm.

Referring now to the drawings, and more particularly to VFIGURES l, 2and 3, there is shown an illustrative embodiment of the invention. AlU-shaped base 22 is mounted in the interior of a llock casing or door41t) to a front plate 12 by means of screws 24 and 26. A handie base 28ismounted on the exterior of the door 10 with the front plate 12 lbymeans of screws 24 and 26 and has a circular opening 29 which iscoaxially aligned ice with a circular opening `13 in the front plate 12.An actuating handle 30 provided with a shaft 32 having a rectangularportion 34 and a cylindrical portion 36 is mounted with the handle base28 such that the cylindricall shaft portion 36 provides a bearingsurface with the walls of the circular opening 429'. 'I'he shaft 32 isaxially secured in place with a bowed retaining ring 38 mounted on anannular groove 40 in the shafts cylindrical portion 36.

The U-shaped base 22 is provided with legs 21. and 23 each having a pairof guide holes extending therethrough coaxially aligned with a pair ofguide holes in the other v leg and serving to guide a pair of axiallymovable rods `46 and 48 disposed in parallel with each other, -as isshown in FIGURE 3. The rods 46 and 4S are provided with rack portions 47and 49 formed thereon, respectively. A pinion 42 having a rectangularhole 44 extending therethrough is rigidly mounted on the rectangularportion 34 of the shaft 32 and maintained in meshing engagement with therack portions 47 and 49. The handle 31B serves to rotate the pinion soas to obtain opposing axial movement of the rods 46 and 48 betweenextended and withdrawn positions.

In FIGURES l and 2 the latch mechanism is shown in its closed positionWith the rods 46 and 48 respectively extending thru apertures 16 and 318in the door 10 and -co-acting with keepers or striker plates and 82mounted on a door frame 84. The rods 46 and 48 have tapered ends whichcam against cam surfaces provided on the striker plates when the rodsare heing extended, as is shown in FIGURE 2 in which the rod 46 having atapered end 45 cams against a cam surface 81 of striker plate 3o so asto pull the door 10 securely against the door iframe 84. A latch arm 50(FIGURE 6) having a canted surface 51 is rigidly fitted with the shaft32 and rotates therewith between the latch mechanisms closed and openedpositions. When the latch arm 50 is rotated toward the closed positionthe canted surface `511 cams with striker plate 86 mounted -on the `doorframe 84 thus providing a three pointilatch mechanism for maintainingthe door 10 secured with the door frame .84.

A lock block S4 (FIGURE 3) having two guide holes extending therethroughis mounted so as to be in sliding engagement with the rods 46 and `48.The guide holes in the lockv block 54 are counter bored providingshoulders 5'6 yand 58 4andthe guide holes in the leg 23:` are counter'bored providing shoulders 60 and 62. Spiral springs 64 and 66 arecoaxially mounted on the rods 46 and 48, respectively, and seatedagainst the shoulders 58 and 62, and 56 and 60, respectively, therebyspring biasing the lock block 54 in engagement with latch arm 50 rigidlyiitted with the shaft 32.l A pull back rod 68 is mounted for slidingengagement with a bore hole 70 in the leg 23 and has a threaded endwhich is screwed into engagement with a threaded hole in the lock block54 so as to adjust the tension of springs 64 and 66. The rod y63 is heldin place with a cotter pin 71.

The latch arm 50 (FIGURE 6) is provided with bearing surfaces 72 and 74which respectively engage a shoulder 55 of the lock block 54 when therods 46 and 48 are in their extended and Withdrawn positions. Acaptivated slide block 76 preferably 4made of nylon is mounted in aco-operating cut-out portion 78 of latch arm 50i and provides a camsurface 77 which cams against the shoulder 55 of the lock block 54 asthe latch Iarm 50 is rotated between the latch mechanisms closed andopened positions. The yblock 76 is held in place in the cut-out portion78 with a shoulder 55 of the lock block 54 and a washer 88 `fitted witha circular hub portion 57 of the latch arm Si).

An understanding of the operation of the three point latch mechanism maybe had from the following description. When the latch mechanism islocked in its closed position, i.e., with latch arm 50 in engagementwith the striker plate y86, and the rods 46 and 4S in engagement withstriker plates 80 and 82, respectively, the lbearing surface 72 is heldin engagement with the lock block 54 by virtue of the tension in springs64 and 66 as shown in FIGURE 3. The latch mechanism will remain lockedin its closed position until a sufficient force is applied to the handle30 Ito overcome the tension of springs 64 and 66. lf the force be suchto rotate the shaft 32 in a counterclockwise direction, the cam surface77 of the captivated slide block 76 will cam against the shoulder 55 ofVthe lock block 54 compressing springs 64 and 65 until the bearingsurface 74 engages the shoulder 55 at which time the springs 64 and 65will flex axially so as to hold the lock block 54 securely lagainst thebearing surface 74. As the shaft 32 is rotated counterclockwise thepinion 42 imparts axial movement to the rods such that the rod 46 ismoved toward the left and the rod 48 is moved .toward the right (FIGURE3) and in so doing are withdrawn from engagement with striker plates 82and 8d, respectively. At the same time, the latch arm 50 is also rotatedcounterclockwise and is disengaged from the striker plate 816. 'Ihelatch mechanism Will remain locked in its opened position until a forceis applied to the handle 30 suflicient to overcome the tension ofsprings 64 and 66.

Although the Vdescription of this invention has been given with respectto a particular embodiment, it is not to be construed in a limitingsense. Numerous variations and modifications within the spirit and scopeof the invention will now occur to those skilled in the art. For adenition of the invention, reference is made to the appended claims.

We claim:

l. A latch mechanism comprising two rods `disposed in parallel andadapted to be mounted Within a door, each rod having a rack portionthereon, a pinion interposed in meshing engagement with the rackportions, an actuating handle fixed with the pinion and serving torotate the pinion so as to obtain opposing axial movement of the rods,the rods being adapted .to engage associated striker plates, guide meansprovided for guiding the rods in parallel with each other as they areaxially moved, a latch arm fixe-d with the handle and rotatable in Ithesame sense as thepinion, the llatch arm being adapted to engage a thirdstri-ker plate, and a spring biased lock block mounted -for slidingengagement with the rods and serving to hold th latch arm locked inposition. i

2. In a latch mechanism having latch opened and closed positions, firstand second rods disposed in parallel i and adapted to be mounted withina door, each rod having a rack portion formed thereon, a pinioninterposed 4in meshing engagement with the rack portions, an actuatinghandle fixed with the pinion and serving to rotate the pinion so as toobtain opposing axial movement of the rods between latch opened andclosed positions, first, second and third striker plates adapted to bemounted on a door frame, the lirst and second rods being in engagementwith the first and second striker plates, respectively, when in latchclosed position, a latch arm fixe-d with the handle and adapted torotate in the `same sense as the pinion between latch opened and closedpositions, the latch arm being in engagement with the third strikerplate when the latch arm is in latch closed position, the latch armhaving first and second bearing surfaces, a lock block mounted forsliding engagement with the rods, first and second spiral springscoaxially mounted on the first and second rods, respectively, andserving to spring bias the lock block into locking engagement with thefirst and second bearing surfaces when the latch ar-m is in latch openedand closed positions, respectively, and a slide block mounted on thelatch arm and having a cam surface interposed between the first andsecond bearing surfaces, the cam surface being adapted to cam againstthe lock block as the latch arm is rotated between latch opened andclosed positions.

3. A latch mechanism comprising rod means including two rods disposedformovement in different directions and adapted to be mounted within adoor, each rod having a rack portion thereon, a pinion interposed inmeshing engagement with the rack portions, an `actuating handle fixedwith the pinion and serving to rotate the pinion so as to obtainsimultaneous axial movement of the rods, the rods being adapted toengage associated striker plates, means for guiding the rods as `theyare axially moved, a latch arm fixed with the handle and rotatable inthe same sense as the pinion, the latch arm being adapted to engage athird striker plate, and a spring biased lock block mounted for slidingengagement with the rod means and serving to hold the latch arm `lockedin position.

References Cited in the tile of this patent UNlTED STATES PATENTS1,398,159 Sontow Nov. 22, 1921 1,693,912 Worthen Dec. 4, 1928 FOREIGNPATENTS 127,761 Germany Feb. 3, 1902 99,743 Switzerland Aug. L27, 1940

3. A LATCH MECHANISM COMPRISING ROD MEANS INCLUDING TWO RODS DISPOSEDFOR MOVEMENT IN DIFFERENT DIRECTIONS AND ADAPTED TO BE MOUNTED WITHIN ADOOR, EACH ROD HAVING A RACK PORTION THEREON, A PINION INTERPOSED INMESHING ENGAGEMENT WITH THE RACK PORTIONS, AN ACTUATING HANDLE FIXEDWITH THE PINION AND SERVING TO ROTATE THE PINION SO AS TO OBTAINSIMULTANEOUS AXIAL MOVEMENT OF THE RODS, THE RODS BEING ADAPTED TOENGAGE ASSOCIATED STRIKER PLATES, MEANS FOR GUIDING THE RODS AS THEY AREAXIALLY MOVED, A LATCH ARM FIXED WITH THE HANDLE AND ROTATABLE IN THESAME SENSE AS THE PINION, THE LATCH ARM BEING ADAPTED TO ENGAGE A THIRDSTRIKER PLATE, AND A SPRING BIASED LOCK BLOCK MOUNTED FOR SLIDINGENGAGEMENT WITH THE ROD MEANS AND SERVING TO HOLD THE LATCH ARM LOCKEDIN POSITION.